The present invention relates to methods and apparatus for taking samples of cells from discrete tissue areas. The taking of such samples is necessary in the cytological diagnosis of suspect tissue areas such as tumors.
Various techniques have been used to take cells from tumors in order to establish whether they are benign or malignant. The choice of a specific technique depends on several factors, including the location and size of the area to be sampled, the susceptibility of the area to complications such as infection, and the ease of use.
One commonly used technique is the so-called core needle biopsy technique wherein a relatively large hollow needle (e.g., 14 gauge) is forced into the tissue to be sampled and then retracted to yield a core sample suitable for histological evaluation. The taking of core needle biopsy specimens is particularly prevalent in the diagnosis of prostatic cancer in the United States. The popularity of this technique is attributed in part to the minimal training required to perform the procedure. In fact, it not infrequently results in complications due to the inevitable traumatization of the tissue by the relatively large needle.
An alternative to the core needle biopsy technique is the so-called fine-needle aspiration technique. Cytological diagnosis with the aid of fine-needle puncture and aspiration started in the late 1950's, when it was shown that individual cells collected from tumors by means of this technique could be recognized and classified. The fine needle aspiration technique offers numerous advantages over core needle biopsy. For example, with respect to the cytological diagnosis of prostatic cancer, fine needle aspiration can be performed as an outpatient procedure without anesthesia or bowel preparation. Further, the patient can be informed of the diagnosis almost immediately and there is an extremely low incidence of complications (1% in 14,000 cases). Moreover, aspiration cytology has proven to be more accurate in prostate cancer diagnosis than conventional core needle histological biopsy. In summary, fine needle aspiration biopsy is an accurate, inexpensive and safe method of diagnosing cancer.
Current fine-needle aspiration apparatus and techniques, however, suffer from several disadvantages, which have contributed to limiting their widespread acceptance in the United States.
U.S. Pat. No. 3,595,217 discloses a method and apparatus for fine needle aspiration biopsy of the prostate. The method and apparatus disclosed in U.S. Pat. No. 3,595,217 are very similar to the method and apparatus commonly used throughout Europe and increasingly used in the United States. However, the disclosed method and apparatus are cumbersome to use, requiring, in practice, at least one highly trained person with an assistant to successfully perform the procedure since the needle is first inserted in the patient, and a syringe is thereafter attached while the operator's hand remains in the patient. Moreover, the disclosed method and apparatus do not readily lend themselves to the use of a stylet during penetration and withdrawal of the needle. Furthermore, the insertion, withdrawal and reciprocation of the needle during the procedure are not precisely determinable since the procedure is performed manually with no means to precisely monitor needle movement. In addition there is a lengthy learning curve that can only be overcome by performing many manual (conventional) fine-needle aspiration biopsies under proper instruction.
U.S. Pat. No. 4,605,011 to Naslund discloses yet another prior art attempt to solve the problems associated with fine-needle aspiration methods and apparatus. The Naslund cell sampling methods and apparatus, however, have several disadvantages. First, because a stylet is not used to occlude the tip of the needle during the aspiration procedure, there is a danger of patient and sample contamination. For example, in prostate aspiration, the absence of a stylet increases the risk of contamination of the aspirated sample and inoculation of the prostate with enteric bacteria present in the rectal vault when the needle is passed through the rectal mucosa into the suspected tumor in the prostrate gland. The Naslund apparatus and method further require that the tip of the biopsy needle be introduced into the suspected tumor without predictability or repeatability, because the operator is unable to precisely determine the forward excursion of the needle when penetrating the target area. Also, the persistence of vacuum in the needle and adjacent connecting tube of Naslund after release of the trigger at the conclusion of the biopsy could tend to cause (i) aspiration of contaminants or debris, such as rectal mucosa and/or bacteria residing in the rectum, and (ii) potential loss of sample into the connecting tube. Furthermore, Naslund employs a single gauge fine needle, thus limiting the total amount and recoverability of cell sample. Accordingly, the Naslund cell sampling apparatus is not well suited for certain applications, such as the cytological diagnosis of prostatic cancer.
Accordingly, it is an object of the present invention to provide an apparatus and method for fine-needle aspiration which simplify and standardize the fine-needle aspiration technique.
It is a further object of the present invention to provide a fine-needle aspiration apparatus and method which allow the needle to be occluded during the penetration and withdrawal stages of the procedure to avoid introducing contaminants into the sample or the region being biopsied.
It is a further object of the present invention to provide a fine-needle apparatus and method which enable a single person to perform the biopsy procedure.
Another object of the present invention is to provide a device capable of performing a fine-needle aspiration biopsy quickly and safely, preferably in an out-patient setting, such as the practitioner's office.
It is a further object of the present invention to provide a fine-needle apparatus and method which will standardize and simplify the aspiration procedure by automatically performing one or more steps of the aspiration procedure.
It is a further object of the present invention to provide a fine-needle aspiration cell sampling apparatus having a failsafe feature which automatically occludes the needle tip, and retracts the needle in emergency circumstances.
It is a further object of the present invention to provide a fine-needle biopsy apparatus which is entirely disposable or in which all parts subject to contamination are disposable.
It is another object of the present invention to provide a fine-needle aspiration apparatus and method which facilitate the collection of cytological samples without coring the tissue in the region being sampled.
It is also an object of the present invention to provide a fine-needle aspiration apparatus and method which facilitate the collection of a sufficient quantity of cells to enable an accurate cytological diagnosis to be made (i.e., malignant vs. benign).
It is a further object of the present invention to provide apparatus and methods which simplify and facilitate the expression of cytological samples retrieved through fine-needle aspiration.
These and other objects will become apparent to those skilled in the art upon reviewing the summary of the invention, and the detailed description and drawings of the preferred embodiments of the invention hereinafter set forth.